Rasie the collective, then twist throttle to prime (3-5) times works well.
Just think about why this works... when your flying, rasing the collective does what? > adds power, right, so more fuel is being allowed to flow.. same princible on the gorund, with collective down, like it would be at ground idle, not as much fule flows as in flight with the collectove up...
thats why haveing the collective up when priming , it works better
Collective up - trees small, collective down trees big.
RB